Crankshaft



CRANKSHAFT Dec. 21, 1937.

Filed Dec. 16, 1955 /n vento/f 35 thickness for directly transmitting the forces a central rib C. Both figures further show short Patented Dec. 21,1937` i y UNITED STATES PATENT, oF'FiCEl- Edmund Rumpler, Berlin-Charlottenburg, Germany Application December 16,1935, Serial No. 54,646

' In Germany February 10,' 1934 7 Claims. (Cl. i4-596) This invention relates' to a hollow crankshaft is a longitudinal| section of a cast hollow crankproduced by casting for use in piston engines. shaft; Fig. 2, across section of a bearing part The invention proposes to produce a hollow on an enlarged scale; and Figs. 3 and 4 are seccrankshaft by casting which makes it possible to tional detail views.

5 impart to this hollow body resembling a tube Referring to the drawing, and first to Fig. 1,r with several bends sufficient inherent stability it will be noted that the wall thicknesses d1, d2, and to manufacture it in a much simpler manda of the journals and the wall thicknesses 191,. ,ner and at lower cost than a sheet 'metal crankwz, ws, wi of the crankshaft pins gradually iri-v shaft. Preferably, material of great strength crease towards the flywheel or working end, as

is used which permits of being refined or harddo also the wall thicknesses of the crank arms 10 ened after casting by surface or through ytreatsi, s2, s3, s4, sa, se. In other words, the wall thickment. I l ness increases with the external forces and mo- The crank shaft together with crank bearing, menta. The conical space thus produced serves crank pins and crank arms is made by casting alsofor reducing the weight. The'external measin one single hollow body, the walls consisting urements being ,alike at the same spots in the 15 throughout of homogeneous material possessing construction shown,the hollow spaces or bores are the same tensile properties and hardness. decreasing of course. The construction shows The invention affords considerable advantages. also a rib R arranged symmetrically with respect The crankshaft consists of a single casting made to the longitudinal axis of the crankshaft and. in one operation at a much lower cost than a extending over the ventire length thereof.

sheet metal crank shaft comprising two or more In the cross` section of a 'bearing part ofthe 20 pieces. Compared with solid .cast crankshafts, a shaft shown in Fig.' 2 the hollow space is eccensaving in weight of approximately 50% or more is trically disposed so as to produce a smaller wall effected, which plays an important part in airthickness D1 and a. larger one D2. This construc- 2 5 craft and vehicle motors and involves also a savtion is chosen when'the permissible stress ofthe 25 ing in material. Furthermore, the crankshaft casting material differs as to tension and comthroughout consists cf homogeneous material pression. Fig. 2 further shows the symmetrically possessing uniform vtensile properties and hardvdisposed rib R. ness, and it can even be made lighter than sheet Fig. 3 shows in longitudinal section a tapering metal shafts by using walls differing in thickness hollow space in a journal, with' the larger wall 30 according to the differences in stress to which thickness towards the working side.

it may be subjected so as'to insure uniform spe- Both Figs. 3 and 4 show inner ribs disposed vercic material stress. `If desired one or several ribs tically to the longitudinal axis of the crankshaft, can be arranged between the walls differing in Fig. 3 disclosing two lateral ribs B1, B2 and Fig. 4,

appearing in the walls. The' ribs can be prolongitudinal ribs RO which give'additional sup'- vided parallel and/or vertically to the longitudiport. nal axis of the shaft and, inthe first instance,` According to Fig. 4, an undivided ringLof steel, extend over the entire length of the shaft. bronze, etc., is provided at a journal, into which 40 The invention provides for the first time a. the crankshaft is cast and which is protected 40v crankshaft having a stress bearing skin, conagainst rotation and displacement. The provision structed preferably as a body having uniform of such a ring or bush makes it possible to use strength. This cast shaft with stress bearing for certain purposes good material of lesser skin makes it possible to render it hollow everystrength including even aluminum alloys, such as where including the webs which hitherto were dural, lautal, or an aluminum-magnesium alloy 45 solid. yMoreover, at the webs as `vwell. as at the "known under the trade-name Electrjhnf K des' bearings and pins the skin can be made so as ignates holes for the proper and secilre arrangeto correspond to different stresses without extra ment of the crank cores.

work or finishing. Casting .affords also the possi- Accordingy t'o the invention,` ythe thin-walled mability of providing the inner 'ribs required for terial of the stress bearing skin of the crankshaft 50 maintaining the form and rigidity of the stress can be reiined accurately and to the exact extent bearing skin; which ribs serve further -for propdesired from the inside or outside, or, simulerly guiding the forces at the bends.l taneously, from both inside and outside, winch By way of example, the invention is illustrated cannot be done with solid material. Refining or in. the accompanying drawing, in which Figure 1 hardening can thus Abe carried out with much 55 greater uniformity and within a shorter time.

The crankshaft according to the invention, in addition to being cooled on the outside, maybe co'oled also from within by forcing oil or air through it. v

iAnother advantage of the invention is that the counterweights are much lighter, too.

I claimt- 1. A crankshaft for piston engines comprising an integral and hollow one-piece cast body, hollow crank bearings and crank pins and4 crank arms in said vbody integrally formed'therewith, said hollow crank bearings, pins and arms forming at least one channel, free from permanent metallic cores including tubes, extending throughout said body and occupying the major portion of the cross section thereof.

2. A crankshaft for piston engines comprising an integral and hollow one-piece cast body adapted to form hollow crank bearings and hollow crank pins and hollow crank arms, said hollow crank bearings and pins and arms forming at least onechannel, free from permanent metallic cores including tubes except for a longitudinal inner rib integrally cast with said body connecting the opposite wall portions of the shaft and directly transmitting the forces developed therein through the shortest distance, said channel extending throughout said body and occupying the major portion of the cross section thereof.

3. A crankshaft for piston engines comprising t an integral and hollow one-piece cast body adapted to form hollow crank bearings and hollow crank pins 'and hollow crank arms, said hollow crank bearings, pins and arms forming at least one channel, free from permanent metallic cores including tubes, extending throughout said body and occupying the major portion of the cross section thereof, said cast body having walls the thickness of which gradually decreases from one end of the shaft to the other in accordance with the decrease o f the forces to be transmitted whereby uniform distribution of the stresses throughout the crankshaft is obtained.

5-. A crankshaft for piston engines comprising an integral and hollow one-piece cast body adapted to form hollow crank bearings and hollow crank pins and hollow crank arms, said body being constituted of a material having dierent compressional and tensional strength, and said hollow crank bearings, pins and arms forming at least one channel, free from permanent metallic cores including tubes, extending throughout said cast body and occupying the major portion of the cross section thereof, said channel being eccentrically arranged in the bearings and pins.

6. A crankshaft for piston engines comprising an integral and hollow one-piece cast bodyA adapted to form hollow crank bearings and hollow crank pins and hollow crank arms, said hollow crank bearings, pins and arms forming at` least one channel, free from permanent metallic cores including tubes, extending throughout said body and occupying the major portion of the cross section thereof, said body being constituted of a light metalalloy.

7. A crankshaft for piston engines comprising an integral and hollow one-piece cast body adapted to form Ahollow crank bearings and hollow crank pins and hollow crank arms and being constituted of a relatively soft alloy, said hollow crank bearings, pins and arms forming at least one channel, free from permanent metallic cores including tubes, extending throughout said body and occupying the major portion of the cross section thereof.

EDMUNDVRUMPLER. 

